Questions for Geology 8T quiz #1 – Be prepared for any of these four questions, however, I
will only ask you two of them.
Here are the potential questions (I will ask you two of these):
1. What is the main difference between the lithosphere and the asthenosphere?
Contrast the oceanic lithosphere and the continental lithosphere.
Each of the following questions related to density will ask you to support a claim using one or more of
the density ideas we developed in class in a graphic organizer like the one shown below. So you
need to know those 4 density ideas.
2. The lithosphere is actually composed of crustal rocks with a layer of higher
density rocks (part of the mantle, but still stiff and rigid) at the base, as
shown to the right. Both parts are attached to each to each other and
behave as a single brittle unit (the lithosphere). Note that the density of the
asthenosphere is 3.3 g/cm3 – thus, the rigid mantle rocks at the base of the
lithosphere have a higher density than the asthenosphere. If the rocks at the
base of the lithosphere are denser than the asthenosphere, then why does the continental
lithosphere float?
Claim: The continental lithosphere floats even though the rocks found at the bottom of the cont.
lith. are more dense than the asthenosphere.
What are the density ideas that support this claim? Clearly explain how they can be applied to
this problem.
continental
crust rocks
(2.67 g/cm3)
mantle rocks
(3.4 g/cm3)
